The cycle life of oxygen carrier (OC) is crucial to the practical applications of chemical looping combustion (CLC).Cycle performance of Cu/SiO2 prepared with a mechanical mixing method was evaluated based on a CLC process characterized with an added methane steam reforming step.The Cu/SiO2 exhibited high redox reactivity in the initial cycles,while the performance degraded with cycle number.Through characterization of the degraded Cu/SiO2,the performance degradation was mainly caused by the secondary particles\' fragmentation and the fine particles\' local agglomeration,which worsened the distribution and diffusion of the reactive gases in the packed bed.A regeneration method of the degraded OC based on re-granulation has been proposed,and its mechanism has been illustrated.With this method,the performance of the degraded OC through 420 redox cycles was recovered to a level close to the initial one.